[one-users] File system performance testing suite tailored to OpenNebula

[Gerry O'Brien]

Hi Carlo,

   Thanks for the reply. I should really look at XFS for the replication 
and performance.

   Do you have any thoughts on my second questions about qcow2 copies 
form /datastores/1 to /datastores/0 in a single filesystem?

         Regards,
           Gerry


On 11/09/2013 12:53, Carlo Daffara wrote:
> It's difficult to provide an indication of what a typical workload may be, as it depends greatly on the
> I/O properties of the VM that run inside (we found that the "internal" load of OpenNebula itself to be basically negligible).
> For example, if you have lots of sequential I/O heavy VMs you may get benefits from one kind, while transactional and random I/O VMs may be more suitably served by other file systems.
> We tend to use fio for benchmarks (http://freecode.com/projects/fio) that is included in most linux distributions; it provides for flexible selection of read-vs-write patterns, can select different probability distributions and includes a few common presets (like file server, mail server etc.)
> Selecting the bottom file system for the store is thus extremely depending on application, feature and load. For example, we use in some configurations BTRFS with compression (slow rotative devices, especially when there are several of them in parallel), in other we use ext4 (good, all-around balanced) and in other XFS. For example XFS supports filesystem replication in a way similar to that of zfs (not as sofisticated, though), excellent performance for multiple parallel I/O operations.
> ZFS in our tests tend to be extremely slow outside of a few "sweet spots"; a fact confirmed by external benchmarks like this one:
> http://www.phoronix.com/scan.php?page=article&item=zfs_linux_062&num=3 We tried it (and we continue to do so, both for the FUSE and native kernel version) but for the moment the performance hit is excessive despite the nice feature set. BTRFS continue to improve nicely, and a set of patches to implement send/receive like ZFS are here: https://btrfs.wiki.kernel.org/index.php/Design_notes_on_Send/Receive but it is still marked as experimental.
>
> I personally *love* ZFS, and the feature set is unparalleled. Unfortunately, the poor license choice means that it never got the kind of hammering and tuning that other linux kernel filesystem can get.
> regards,
> carlo daffara
> cloudweavers
>
> ----- Messaggio originale -----
> Da: "Gerry O'Brien" <gerry at scss.tcd.ie>
> A: "Users OpenNebula" <users at lists.opennebula.org>
> Inviato: Mercoledì, 11 settembre 2013 13:16:52
> Oggetto: [one-users] File system performance testing suite tailored to	OpenNebula
>
> Hi,
>
>       Are there any recommendations for a file system performance testing
> suite tailored to OpenNebula typical workloads? I would like to compare
> the performance of zfs v. ext4. One of the reasons for considering zfs
> is that it allows replication to a remote site using snapshot streaming.
> Normal nightly backups, using something like rsync, are not suitable for
> virtual machine images where a single block change means the whole image
> has to be copied. The amount of change is to great.
>
>       On a related issue, does it make sense to have datastores 0 and 1
> in a single files system so that the instantiations of non-persistent
> images does not require a copy from one file system to another? I have
> in mind the case where the original image is a qcow2 image.
>
>           Regards,
>               Gerry
>


-- 
Gerry O'Brien

Systems Manager
School of Computer Science and Statistics
Trinity College Dublin
Dublin 2
IRELAND

00 353 1 896 1341